Provided by: libexplain-dev_1.4.D001-8_amd64 bug

NAME

       explain_listen - explain listen(2) errors

SYNOPSIS

       #include <libexplain/listen.h>
       const char *explain_listen(int fildes, int backlog);
       const char *explain_errno_listen(int errnum, int fildes, int backlog);
       void explain_message_listen(char *message, int message_size, int fildes, int backlog);
       void explain_message_errno_listen(char *message, int message_size, int errnum, int fildes,
       int backlog);

DESCRIPTION

       These functions may be used to obtain explanations for errors returned  by  the  listen(2)
       system call.

   explain_listen
       const char *explain_listen(int fildes, int backlog);

       The  explain_listen  function is used to obtain an explanation of an error returned by the
       listen(2)  system  call.   The  least  the  message  will  contain   is   the   value   of
       strerror(errno),  but usually it will do much better, and indicate the underlying cause in
       more detail.

       The errno global variable will be used to obtain the error value to be decoded.

       This function is intended to be used in a fashion similar to the following example:
              if (listen(fildes, backlog) < 0)
              {
                  fprintf(stderr, "%s\n", explain_listen(fildes, backlog));
                  exit(EXIT_FAILURE);
              }

       The above code example is available pre‐packaged as the explain_listen_or_die(3) function.

       fildes  The original fildes, exactly as passed to the listen(2) system call.

       backlog The original backlog, exactly as passed to the listen(2) system call.

       Returns:
               The message explaining the error.  This message buffer is shared by all libexplain
               functions  which  do  not  supply  a  buffer in their argument list.  This will be
               overwritten by the next call to any libexplain function which shares this  buffer,
               including other threads.

       Note:  This  function  is  not  thread  safe, because it shares a return buffer across all
       threads, and many other functions in this library.

   explain_errno_listen
       const char *explain_errno_listen(int errnum, int fildes, int backlog);

       The explain_errno_listen function is used to obtain an explanation of an error returned by
       the  listen(2)  system  call.   The  least  the  message  will  contain  is  the  value of
       strerror(errnum), but usually it will do much better, and indicate the underlying cause in
       more detail.

       This function is intended to be used in a fashion similar to the following example:
              if (listen(fildes, backlog) < 0)
              {
                  int err = errno;
                  fprintf(stderr, "%s\n", explain_errno_listen(err, fildes, backlog));
                  exit(EXIT_FAILURE);
              }

       The above code example is available pre‐packaged as the explain_listen_or_die(3) function.

       errnum  The  error  value  to  be decoded, usually obtained from the errno global variable
               just before this function is called.  This is necessary if you need  to  call  any
               code  between the system call to be explained and this function, because many libc
               functions will alter the value of errno.

       fildes  The original fildes, exactly as passed to the listen(2) system call.

       backlog The original backlog, exactly as passed to the listen(2) system call.

       Returns:
               The message explaining the error.  This message buffer is shared by all libexplain
               functions  which  do  not  supply  a  buffer in their argument list.  This will be
               overwritten by the next call to any libexplain function which shares this  buffer,
               including other threads.

       Note:  This  function  is  not  thread  safe, because it shares a return buffer across all
       threads, and many other functions in this library.

   explain_message_listen
       void explain_message_listen(char *message, int message_size, int fildes, int backlog);

       The explain_message_listen function may be used to  obtain  an  explanation  of  an  error
       returned by the listen(2) system call.  The least the message will contain is the value of
       strerror(errno), but usually it will do much better, and indicate the underlying cause  in
       more detail.

       The errno global variable will be used to obtain the error value to be decoded.

       This function is intended to be used in a fashion similar to the following example:
              if (listen(fildes, backlog) < 0)
              {
                  char message[3000];
                  explain_message_listen(message, sizeof(message), fildes, backlog);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       The above code example is available pre‐packaged as the explain_listen_or_die(3) function.

       message The location in which to store the returned message.  If a suitable message return
               buffer is supplied, this function is thread safe.

       message_size
               The size in bytes of the location in which to store the returned message.

       fildes  The original fildes, exactly as passed to the listen(2) system call.

       backlog The original backlog, exactly as passed to the listen(2) system call.

   explain_message_errno_listen
       void explain_message_errno_listen(char *message, int message_size, int errnum, int fildes,
       int backlog);

       The explain_message_errno_listen function may be used to obtain an explanation of an error
       returned by the listen(2) system call.  The least the message will contain is the value of
       strerror(errnum), but usually it will do much better, and indicate the underlying cause in
       more detail.

       This function is intended to be used in a fashion similar to the following example:
              if (listen(fildes, backlog) < 0)
              {
                  int err = errno;
                  char message[3000];
                  explain_message_errno_listen(message, sizeof(message), err,
                      fildes, backlog);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       The above code example is available pre‐packaged as the explain_listen_or_die(3) function.

       message The location in which to store the returned message.  If a suitable message return
               buffer is supplied, this function is thread safe.

       message_size
               The size in bytes of the location in which to store the returned message.

       errnum  The  error  value  to  be decoded, usually obtained from the errno global variable
               just before this function is called.  This is necessary if you need  to  call  any
               code  between the system call to be explained and this function, because many libc
               functions will alter the value of errno.

       fildes  The original fildes, exactly as passed to the listen(2) system call.

       backlog The original backlog, exactly as passed to the listen(2) system call.

SEE ALSO

       listen(2)
               listen for connections on a socket

       explain_listen_or_die(3)
               listen for connections on a socket and report errors

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2008 Peter Miller

                                                                                explain_listen(3)